1. Field of the Invention
The present invention relates to an image processing apparatus, a computer-readable recording medium including an image processing program, and an image processing method, and particularly relates to an image projection display method in an image projection display device.
2. Description of the Related Art
In order to display information for a plurality of people, for example, in meetings, lectures, or presentations, it is conventionally common to use a projection device such as a projector to enlarge and project an image or a moving image showing necessary information onto a wall or a screen, and to give an explanation. In such situations in which the projection device is used, there are cases in which a speaker or a listener wants to write additional information to the above-mentioned image, or wants to designate or point a particular part of the projected image. There have already been contrived and known methods that allow the speaker or the listener to conduct the above-described action in the above-described cases by using a pointing stick or a speaker's or listener's own finger.
As one of such methods, there is known, as described in Japanese Patent No. 3729533, a pointing system that displays a trajectory traced by a user using a pointing stick on a screen with a projected image, as an image superimposed on the screen. As another method, there is known, as described in Japanese Patent Application Laid-open No. H7-129322, a computer display system that determines a button is pressed when a shadow of a pointing stick is placed at a position corresponding to an object image representing the button that is projected on a screen.
With the method described in Japanese Patent No. 3729533, the image can be drawn on the screen by the user who simply traces the screen with the pointing stick. However, the tip of the pointing stick needs to be in contact with the screen; therefore, the user needs to prepare a long pointing stick so as to prevent the user from entering a projection optical path. Therefore, the method described in Japanese Patent No. 3729533 has a problem that the pointing system functions merely as an ordinary projection device and cannot add or draw an image on the screen unless such a long pointing stick can be prepared.
With the method described in Japanese Patent Application Laid-open No. H7-129322, the above-described problem in Japanese Patent No. 3729533 does not occur because the user can achieve the same effect as the pressing of the button or can perform an operation by simply placing the shadow of the pointing stick or a finger at the image projected on the screen. However, with the method described in Japanese Patent Application Laid-open No. H7-129322, it is necessary to place, instead of the pointing stick or the finger itself, the shadow of the pointing stick or the finger at a designated position of the projected image while comprehensively taking into consideration a projection angle and a projection range of the image projected from the projection device, a standing position of the user, and the like. Therefore, there is a problem that the user cannot perform intuitive operations and needs skills and expertise to make full use of the system.
Hence, as described in Japanese Patent Application Laid-open No. 2009-070245, an image projection display device is known that projects an image from the rear side of a screen to allow a user to perform an operation by tracing the front surface of the screen while watching transmitted light of the projected image. Unlike the methods described in Japanese Patent No. 3729533 and Japanese Patent Application Laid-open No. H7-129322, because of being a rear-projection device, the image projection display device described in Japanese Patent Application Laid-open No. 2009-070245 prevents the user from intercepting the projection optical path, and enables the user to perform intuitive operations by directly touching the screen with a finger. Thus, with the image projection display device described in Japanese Patent Application Laid-open No. 2009-070245, there is no occurrence of the above-described problems occurring in Japanese Patent No. 3729533 and Japanese Patent Application Laid-open No. H7-129322. However, the image projection display device described in Japanese Patent Application Laid-open No. 2009-070245 has a problem of requiring an expensive screen that differs from ordinary screens and that is dedicated to the device.
The present invention has been made in order to solve such problems, and it is an aim of the present invention to allow a user to perform intuitive operations when the user performs the operations on an image projected on a screen with a low-cost and simple configuration.